FVM - Level 3 instruments: Sensitivity to changes in unobservable input assumptions (Detail) - USD ($) $ in Millions	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024
Disclosure Of Sensitivity Analysis Of Fair Value Measurement To Changes In Unobservable Inputs Assets And Liabilities [Line Items]
Favorable changes	$ 1,830	$ 1,785	$ 2,056
Unfavorable changes	(1,601)	(1,528)	(1,700)
Loans at fair value (held for trading and not held for trading) and guarantees
Disclosure Of Sensitivity Analysis Of Fair Value Measurement To Changes In Unobservable Inputs Assets And Liabilities [Line Items]
Favorable changes	141	147	185
Unfavorable changes	(112)	(115)	(143)
Securities financing transactions
Disclosure Of Sensitivity Analysis Of Fair Value Measurement To Changes In Unobservable Inputs Assets And Liabilities [Line Items]
Favorable changes	25	25	30
Unfavorable changes	(14)	(20)	(24)
Auction rate securities
Disclosure Of Sensitivity Analysis Of Fair Value Measurement To Changes In Unobservable Inputs Assets And Liabilities [Line Items]
Favorable changes	8	8	8
Unfavorable changes	(4)	(6)	(6)
Asset-backed securities
Disclosure Of Sensitivity Analysis Of Fair Value Measurement To Changes In Unobservable Inputs Assets And Liabilities [Line Items]
Favorable changes	19	23	32
Unfavorable changes	(17)	(18)	(28)
Equity instruments
Disclosure Of Sensitivity Analysis Of Fair Value Measurement To Changes In Unobservable Inputs Assets And Liabilities [Line Items]
Favorable changes	387	348	333
Unfavorable changes	(370)	(314)	(308)
Investment fund units
Disclosure Of Sensitivity Analysis Of Fair Value Measurement To Changes In Unobservable Inputs Assets And Liabilities [Line Items]
Favorable changes	178	176	179
Unfavorable changes	(180)	(178)	(181)
Loan commitments measured at FVTPL
Disclosure Of Sensitivity Analysis Of Fair Value Measurement To Changes In Unobservable Inputs Assets And Liabilities [Line Items]
Favorable changes	13	15	38
Unfavorable changes	(41)	(47)	(42)
Interest rate derivative contracts, net
Disclosure Of Sensitivity Analysis Of Fair Value Measurement To Changes In Unobservable Inputs Assets And Liabilities [Line Items]
Favorable changes	68	77	115
Unfavorable changes	(58)	(65)	(70)
Credit derivatives, net
Disclosure Of Sensitivity Analysis Of Fair Value Measurement To Changes In Unobservable Inputs Assets And Liabilities [Line Items]
Favorable changes	78	88	112
Unfavorable changes	(108)	(108)	(117)
Foreign exchange derivatives, net
Disclosure Of Sensitivity Analysis Of Fair Value Measurement To Changes In Unobservable Inputs Assets And Liabilities [Line Items]
Favorable changes	6	4	3
Unfavorable changes	(5)	(3)	(2)
Equity / index derivatives, net
Disclosure Of Sensitivity Analysis Of Fair Value Measurement To Changes In Unobservable Inputs Assets And Liabilities [Line Items]
Favorable changes	690	619	732
Unfavorable changes	(577)	(503)	(617)
Other
Disclosure Of Sensitivity Analysis Of Fair Value Measurement To Changes In Unobservable Inputs Assets And Liabilities [Line Items]
Favorable changes	216	256	289
Unfavorable changes	$ (115)	$ (152)	$ (161)

Disclosure Of Sensitivity Analysis Of Fair Value Measurement To Changes In Unobservable Inputs Assets And Liabilities [Line Items]